Fibroblast Mr 72,000 gelatinase/type IV collagenase is presumed to play a role in the biological degradation of type I Collagen breakdown will occur in various metabolic processes involving the breakdown of soft connective tissue, including in periodontal diseases. To study the actual participation of Mr 72,000 gelatinase, a model system will be used, consisting of live human fibroblasts on a collagen film. Monoclonal and polyclonal antibodies that are found to inhibit gelatinase activity, as well as newly developed synthetic inhibitors, will be tested in this system for ability to block the breakdown of the collagen fragments produced by the action of the collagenase known to be present in the cells. Thus, gelatinase will need to be isolated in milligram quantities and new detection methods will need to be developed. The enzyme will be tested for its specificity towards substrates found in the extracellular matrix, as well as its specificity towards synthetic peptide substrates. Antibodies to gelatinase will need to be raised. The effect of inhibitors of lysosomal proteases will also be studied in the system to distinguish the action of extracellular proteases from an internal processing of collagen fragments. The model system will be refined to remove the need for exogenously added protease, so that the mode of action of gelatinase may be more directly investigated. The regulation of secretion of gelantinase and possible co-regulation with collagenase will be studied by protein levels, mRNA levels, and by immunofluorescence. Regulators such as phorbol esters, interleukin 1, extracellular matrix components, and trypsin will be investigated. The existence and move of activation of a possible proenzyme will be examined.